On-Demand PrEP Use is Highly Effective for Preventing HIV in High-Risk MSM

Results from Prevenir, an ongoing observational study, presented at AIDS 2018, provided further evidence that on-demand PrEP is an effective strategy for preventing HIV acquisition in at-risk men who have sex with men (MSM).

On-demand PrEP—which involves taking a pill containing tenofovir plus emtricitabine (TDF/FTC) before and after sex rather than daily—was previously evaluated in the IPERGAY study, which included a cohort of 1435 at-risk, HIV-negative individuals, nearly all of them MSM, in the Paris region. The Prevenir study builds on these results.

A total of 3000 HIV-negative, high-risk adults are being recruited for the study. Eligibility requirements included inconsistent condom use, creatinine clearance >50 mL/mn, and HbS Ag negative. Participants were allowed to choose between receiving TDF/FTC daily or on demand and could switch regimens during the study. The study objective was to show >15% reduction of new HIV diagnoses in comparison with the numbers provided by the National Surveillance network in 2016.

Jean-Michel Molina (University of Paris Diderot) provided an interim report of 1628 study participants. At enrollment, 45.4% of participants used PrEP daily and 54.6% used it on demand. To date, the study has found no breakthrough HIV infections among men in either group, supporting continued use of both dosing regimens. Furthermore, 85 HIV infections were averted. Rates of correct PrEP use were high, and no study participants discontinued PrEP for drug-related adverse events. —Kara Rosania